Calcium sulfate has been clinically used for many years as a bone void filler with successful results. A preliminary patentability search produced the following patents which appear to be relevant to the present invention:
Hanker et al., U.S. Pat. No. 4,619,655, issued Oct. 28, 1986, discloses an animal implant comprising a scaffold material composed of plaster of Paris and a non-bioresorbable calcium material (such as calcium phosphate ceramic particles) bound with the plaster of Paris; a method of inserting such a composition in fluid or semisolid form into the appropriate body location of an animal (e. g., about a fracture locus); and a method of inserting a preform of such composition into the appropriate location of an animal (e.g., at the locus of a fracture).
Gitelis, U.S. Pat. No. 5,147,403, issued Sep. 15, 1992, discloses a method or technique for implanting a prosthesis comprising the steps of first preparing the surface of a bone to receive the prosthesis, then applying a calcium sulfate suspension in free flowing form to the prepared bone surface, and then seating the prosthesis to the coated bone surface.
Randolph, U.S. Pat. No. 5,614,206, issued Mar. 25, 1997, and U.S. Pat. No. 5,807,567, issued Sep. 15, 1998, disclose processes for preparing pellets by mixing of calcium sulfate, water and other medicaments to provide controlled release of calcium sulfate and medicaments.
Snyder, U.S. Pat. No. 5,425,769, issued Jun. 20, 1995, discloses a composition for an artificial bone substitute material consisting of collagen in a calcium sulfate matrix which can be rendered porous by a foaming agent. The composition is adaptable for osseous repair by adjusting the collagen and calcium sulfate in varying ratios to suit particular applications and including admixtures of growth factors.
Sottosanti, U.S. Pat. No. 5,366,507, discloses a composition for use in bone tissue regeneration, the composition containing a barrier material and a graft material. The barrier material can be calcium sulfate, while the graft material may consist of a composite graft material containing demineralized, freeze-dried, allogeneic bone and calcium sulfate.
Sottosanti, U.S. Pat. No. 5,569,308, discloses a method for use in bone tissue regeneration including first filling a graft site with graft material, and then placing a layer of barrier material over at least a portion of the graft material. The barrier material can be calcium sulfate, while the graft material may consist a composite graft material containing demineralized, freeze-dried, allogeneic bone and calcium sulfate.
Hanker et al, “Setting of Composite Hydroxylapatite/Plaster Implants with Blood 5 for Bone Reconstruction,” Proceedings of the 44th Annual Meeting of the Electron Microscopy Society of America, Copyright 1986, discloses using blood as the only moistening agent in a plaster or plaster/HA mixture as long as accelerator salts are utilized, and suggests that the putty-like consistency of such compositions offers distinct advantages in moldability and workability.
Osteotech, Inc., of Shrewsbury, N.J., markets a bone graft substitute under the mark Grafton®. It is comprised of demineralized bone matrix and glycerol as a carrier material. The carrier material, glycerol, is a viscous, gel-like, weak alcohol that is hydrophilic and water-soluble. It is recognized by the Food and Drug Administration as a “Generally Regarded As Safe” substance.
DePuy, Inc., of Warsaw, Ind., markets a bone graft substitute under the mark DynaGraft®. It is comprised of demineralized bone matrix and poloxamer as a carrier material. Poloxamer is a reverse phase polymer which becomes more viscous with increasing temperature.
Nothing in the known prior art discloses or suggests a bone graft substitute composition including calcium sulfate, a mixing solution such as sterile water, and a plasticizing substance such as carboxymethylcellulose, and having an extended set time and sufficient robustness to withstand fluid impact with minimal erosion.